This invention relates to a method for forming a gas chamber containing pressurized gas therein in a closed-type container such as a hydropneumatic shock absorber or a gas spring.
It is publicly known to introduce pressurized gas into a closed-type container such as a hydropneumatic shock absorber or a gas spring by forming a small hole or an orifice in the wall or the container, introducing pressurized gas into the container through the orifice, and closing the orifice permanently by welding or the like with or without inserting a closure member such as plug or pin into the orifice. Such method is described in, for example, British Pat. No. 996356 or U.S. Pat. No. 3,081,587. However, such prior art methods have shortcomings that it is troublesome and expensive to form gas filling orifice in the wall of the container and to perform gas filling operation after assembling operation, further, the equipment for performing the method is complicated and expensive.